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Product Certification for Hazardous Areas

"I'm looking for an intrinsically safe ..." is often the opening phrase we encounter in conversations with many of our clients..

In an attempt to make sure that we understand their real needs, and at the same time ensure that their purchase will meet their actual requirements, we often end up debunking many myths and providing a lot of detail on the journey to assisting clients in making an informed decision. Some of these include:

  • Why can't I just use my AppleTM device in a waterproof case?
  • The 'intrinsically safe' case - does it really exist?
  • I've seen an ex-certified item on a US website, can I use it here in Australia?
  • Can you tell me what level of safety (or Zone rating) I need?

Just as it isn't easy to manufacture a device for use in a potentially hazardous environment, understanding the maze of different standards, zones, divisions, temperature classifications and markings is something of a nightmare for those trying to find the right equipment that meets the required standards for their application. What follows therefore is an attempt to answer some of the many questions regularly posed by our clients relating to:

Explosion Elements

Before we go on, a few disclaimers about the material provided:

The material provided is intended as general information only, and not in any way specific to particular situations or circumstances. You should always consult with and follow the regulations of your workplace under the guidance of a suitably qualified and endorsed hazardous area assessor or compliance officer before using any electrical equipment in a potentially hazardous area.

Finally, if you're just wanting the quick answer to those questions raised above, you can zip through to the end and find our answers here.

Secondly, this is not meant to be an engineering discussion paper. If you are looking for those, there are lots of other resources of that type around. Instead, this is as close to a layman's outline of the relevant information as is possible given the nature of the topic. Should you find any errors or omissions with this document, please notify us, and we will do our best to include your suggestions where relevant.

With that said, please read on...

Major standard & assessment systems:

  • IECEx Scheme - a system of conformance aimed at harmonising standards to IEC;
  • ATEX (ATmosphères EXplosibles) - Mandatory in the European Union and used widely outside of the EU;
  • NEC (National Electrical Code) and CSA (Canadian Standards Association) - Used in North America.
The IECEx Scheme

The IECEx Scheme is an international Conformity Assessment Scheme covering Electrical Equipment for Explosive Atmospheres, as the internationally accepted means of demonstrating conformity with IEC Standards prepared by IEC TC31. IECEx is about giving confidence that a product or service meets clearly defined transparent criteria. It's aim is to harmonise standards to allow free movement of goods by establishing a world-wide accepted standard. This will result in a single set of standards, a single certificate and a single mark. The benefits of the scheme are obvious – shorter certification lead-times, and the opening up of new markets with no (or very little) need for additional testing and assessment to satisfy national standards. It is limited specifically to electrical equipment only.

IECEx Logo

As opposed to ATEX, IECEx has been made from the outset as a Type 5 Certification Scheme, relying on a single third party to bring together all aspects of design and production control before issuing a publicly available Hazardous Area Certification. Thus the public domain documentation is a certificate issued by the certification body. Furthermore, because of the online IECEx database, any purchaser of the equipment can check the current status of the certificate on the web.

For Australia: Australia has accepted IECEx as the basis for its national standards (AUSEx). Equipment certified to IECEx can be used almost without exception in Australia without the need for further testing or hazardous area approvals. Note: IECEx does not cover general electrical compliance in Australia (RCM Mark).

Unfortunately, while many countries 'accept' IECEx, they have not harmonised their own national standards in line with IECEx, meaning the actual worldwide acceptance of IECEx is not as close as it may seem to be. As most of the world's certified equipment is manufactured in Europe and the USA, the national standards of these countries are a manufacturers first choice for certification, although dual certifying to ATEX and IECEx in Europe is fast becoming the norm.

The ATEX Directive

Since July 2003, Ex products that are placed on the European market must be certified to the ATEX directive (ATEX 94/9/EC). ATEX harmonised the individual certification requirements of the previously separate European countries. ATEX certification involves a detailed process of examination, testing and assessment of equipment intended for use in potentially hazardous areas, with the end result being the issue of an ATEX certificate and report, confirming and demonstrating that the product is safe to use (within certain parameters) within potentially explosive atmospheres. The certification process must be undertaken by a 'Notified Body' who issue ATEX certificates and conduct periodic surveillance of quality management systems

ATEX Logo

For Australia: Australia does not natively recognise ATEX for a number of reasons. Chief among these is the concern that the Document of Conformity (DoC) or certificate of Conformity (CoC), which is the only public domain document that is required can be issued by the manufacturer, who is responsible for it. This effectively allows manufacturers to 'self-certify' or declare the equipment to be safe. By definition, certification is the action of a third party (see ISO/IEC Guide 2) and clearly this leaves the system open to abuse where the DoC is the action of the first party and therefore falls outside the definition of certification.

ATEX equipment can be used in Australia with evidence that the device has been tested by a recognised third party or 'Notified Body' and where the manufacturer holds a QA manufacturing certificate to ISO standards. This qualification is performed by an Australian assessor on behalf of the company intending to use the device and a Conformity Assessment Document (CAD) is issued certifying that the device has met the basic requirements for an IECEx or AUSEx certificate.

US / Canadian Standards

The Canadian Electrical Code and U.S. National Electrical Code IEC 60079-10 mandate the standards for hazardous area devices in North America. These standards are slowly changing to fall into line with IECEx. Until recently it was impossible to accurately draw parallels between the North American system of Classes and Divisions and those of ATEX and IECEx, however Canada has now fully adopted the 3 Zone system for new equipment and US products can continue to be labelled either way.

UL CSA Logo

For Australia: Australia does not recognise the system of Classes and Divisions and any usage of equipment certified to North American standards must have a CAD (see above) completed for each device type and use case.

So what are these Zones all about?

Hazardous Area Zones

Zones are a method of identifying the potential risk based solely on the presence of the flammable substance (gas / dust) under normal conditions. So the closer you get to a flammable substance, or the more likely for a substance to be present, the higher the risk and conversely the lower the zone rating. See the following chart which shows the zones under both IECEx / ATEX and the North American system of Divisions.

Ex Zones

Producing portable devices for Zone 0 applications is extremely difficult and the need for workers to operate in these dangerous conditions is generally kept to an absolute minimum for obvious reasons. Areas where potentially explosive liquids, gases or dust are being produced, refined or where some repeated contact is likely are generally classified as Zone 1. Conversely, examples of Zone 2 areas are storage areas, maintenance workshops and other ancilliary areas adjacent to the main production areas.

Equipment intended for use in a particular Zone must meet the standards of testing for that Zone. So while a Zone 1 certified device can be used safely in either Zone 1 or 2, it cannot be taken into a Zone 0 area. Consequently, Zone 2 certified devices must be introduced with caution into well defined / separated areas if the facility also includes Zone 1 or Zone 0 areas.

Temperature Classifications

When a gas is heated above its ignition temperature it may spontaneously ignite, and the ignition temperature varies with each particular gas. Consequently, devices used in potentially hazardous areas are tested under fault conditions and classified into temperature (‘T’) classes depending on their ability to maintain a maximum permitted surface temperature.

Temperature Classes

Protection Concepts

This is an area of major confusion for many of our customers, caused mostly by the use of incorrect terms or limited knowledge of what it takes to make a device safe for use. The term 'intrinsically safe' is often used when requesting equipment, but this is only one method of ensuring safety of an electrical piece of equipment.

The method selected by a manufacturer to make a piece of equipment safe should be driven by the way it is to be used, and the relative pros and cons of the functionality of the device. Some of these are obvious, for example, it would be impossible to render a mobile device safe using the protection concept of oil-immersion (o). Others are less obvious; you could for example fill a standard computer or phone full of quartz sand (q) and make it safe, but what would the effect of that sand have on the weight or the wear and tear on sensitive electronic components inside the device, not to mention the issues presented when it needs repair? 

Making mobile devices safe

A mobile device such as a computer, tablet or phone presents unique challenges in terms of making it safe.

  • Many of the standards and testing requirements were originally written well before anyone thought of walking into a hazardous area with a mobile phone. Getting these standards changed, agreed upon and updated is a lengthy and time consuming business.
  • Everyone wants the device to be as small and light as the latest consumer product, however your current smartphone doesn't have to survive a drop of a metre onto concrete and not generate enough heat while you're on that 20 minute call to ignite hydrogen!
  • Making a large screen legible in daylight is easy when you can throw any amount of current at it, but not so if you are making it intrinsically safe (i) by limiting the current in the device.

The table below shows the various types of protection and the concepts or methods used in each case. The symbol for each type must be shown as part of the device markings.

Protection Concepts

Device Markings

So you have a ex-certified device, but what do those hazardous markings mean?

We've included a table below which breaks down the IECEx and ATEX codes to help you try and make sense of them. Note that when viewing ATEX device markings, in the wisdom designed to dumb-found mere mortals, the Equipment or 'Device Category' is expressed as a numeric value 1, 2 or 3. This should not be confused with the Zone it is intended to be used in, as Zone 0 = Category 1, Zone 1 = Category 2, etc. 

IECEx / ATEX markings

The Answers

Hopefully the above has been helpful in answering some of your questions in this area. If you've read all the way through, you should already know the answers to the questions at the top of the page, however if you've cheated and pressed the link, here are our answers to those questions:

  • Why can't I just use my AppleTM device in a waterproof case?
    • Answer: Explosion safety isn't just about not letting an explosive gas in. It's as much about what happens when the device has a fault. A weatherproof case can't possibly contain the heat from a short circuited battery reaching the gas atmosphere. You need a specialist flameproof or Exd case to accomplish that. However, as AppleTM products don't like being subjected to heat, and will turn off automatically as designed by the manufacturer, imagine the reaction of that same device to being placed in a almost totally sealed case. Exd cases might be fine in colder climates, but Australian customers have told us otherwise...
  • The 'intrinsically safe' case - does it really exist?
    • Answer: No. As you would have seen above, intrinsic safety is about limiting the currents within the device so that it is incapable of holding or generating sufficient energy to cause an explosive event to occur.
  • I've seen an ex-certified item on a US website, can I use it here in Australia?
    • Answer: Possibly. If it is certified to IECEx, then the item will generally meet the standards for use in most hazardous area gas and dust applications in Australia. If the device is not certified to IECEx, you will need to request a qualified hazardous area inspector or assessor to perform a conformity assessment to determine whether the standards and methods used in the original certification are deemed to conform with those demanded for use in Australia. If successful, they will be abe to grant a Conformity Assessment Document (CAD) permitting you to use the device within specific parameters.
  • Can you tell me whether I should purchase a Zone 1 or Zone 2 device?
    • Answer: No. Equipment manufacturers or agents do not have the requisite site experience or approvals to determine the risk attributed to a site or plant area. You should always consult a qualified hazardous area assessor, with experience of the particular risk profile of the site in question to determine the correct Zone rating for installed and mobile equipment to be used in a particular area. Keep in mind that unless there are specific logistical barriers in place between differently zoned areas, mobile devices are inherantly 'mobile', as they are carried by personnel. As a Zone 2 area instantly becomes a Zone 1 (or Zone 0) area when flammable gas or dust is actually present, and mobile devices are often called upon in times of emergency, using a mobile device with the highest safety protections is something we highly encourage.

If you'd like further assistance, please don't hesitate to contact us.